In the medical field, an image created by imaging technology such as X-ray computed tomography (CT), scanning-type nuclear magnetic resonance imaging (MRI), and digital subtraction angiography (DSA), after being converted to a digital image and magnified by a designated multiplier by means of a variable density image (grey scale image) processing apparatus, is broken down into its constituent graphic elements. The digital image data, containing that image's continuous series of gradients, is converted into a chronological series of analogue signals. An apparatus called a laser imager (hereinafter termed a "variable density image photographic apparatus") then uses a semi-conductor laser apparatus (cf. FIG. 20), employing a direct modulation formula, to irradiate silver-sodium film with these analogue signals, thus making them into photographs.
Each original image includes within it certain data specific to itself, as for example its identification number, patient name, or the date the image was created (cf. FIG. 21). However, the laser beams of the optical systems used in these variable density image (grey scale image) photographic apparatus range between about 80 .mu.m and 100 .mu.m in diameter; in consequence, a written (i.e. alphabetic or numeric) character of the 16-dot size commonly used, for instance, comes out to a size of approximately 1.2 mm when inscribed by such a beam. As a result, a reader cannot decipher the data on the film simply by looking at the film.
Thus, at present, data used for identification of individual films (hereinafter termed "identifying data") is input by means of the variable density image (grey scale image) processing apparatus input apparatus, and is inscribed onto the bottom of the film in a fixed size by means of the optical system; or, alternatively, an identification label is affixed to the bottom of the film following development. Although the data is then readable, the process interferes with the rapid handling of such medical films.
In their typical configurations, the basic constituents of the variable density image (grey scale image) photographic apparatus currently in use are as follows:
(1) a film feeding cassette for storage of film prior to exposure; PA1 (2) a pick-up mechanism to remove the film from the film feeding cassette; PA1 (3) a feeding means for feeding the film removed by this pick-up mechanism to the target location of the laser beam; PA1 (4) an exposure means to expose the film by scanning it while irradiating it with a laser beam; PA1 (5) a film securing means to secure the film; PA1 (6) a secondary scanning means to scan the film in a direction perpendicular to the laser beam's direction of scan; PA1 (7) a retrieval means for retrieving the exposed film; PA1 (8) a film retrieval cassette for storage of film following retrieval; PA1 (9) an image processing means for laser-scan modulation, assembling of image data, and image enlargement and reduction; PA1 (10) a control means for control of laser output and other means; PA1 (11) a power supply means for the controls, for laser output, and for operating the apparatus. PA1 identify data specific to the multiple images are extracted therefrom; PA1 enlarge the extracted identifying data by a designated multiplier; and PA1 the enlarged identifying data at a designated location on the photosensitive medium.
FIGS. 22-26 show examples of variable density image (grey scale image) photographic apparatus configured from the constituents described above.
FIG. 22 depicts a variable density image (grey scale image) photographic apparatus i, consisting of a film feeding cassette a, a film retrieval means b, an exposure means c, an image processing means d, and a control/power supply means e, configured from top to bottom in that order, and a film securing drum f, located next to the image processing means d. The various means in the variable density image (grey scale image) photographic apparatus i in FIG. 22 are thus stacked one on top of another, resulting in a height of approximately 1,200 mm and a weight of some 290 kg. Symbol p in FIG. 22 represents a pick-up mechanism, and g represents a film conveyor means which feeds and also retrieves the film.
FIG. 23 depicts a variable density image (grey scale image) photographic apparatus i, consisting of a film feeding cassette a, an exposure means c, a film shape adjustment space s, a film securing and conveying means h which both secures and conveys the film, and an image processing, control, and power supply means j, configured from top to bottom in that order, and with a separate automatic development apparatus placed next to the variable density image (grey scale image) photographic apparatus. The film which has been developed by this automatic developer is retrieved in the tray t, located on top of variable density image (grey scale image) photographic apparatus i. Thus FIG. 23's variable density image (grey scale image) photographic apparatus, like that shown in FIG. 22, has its components stacked one on top of another; moreover, there is a film shape adjustment space s located between exposure means and film-securer and conveyor means h, resulting in a height of approximately 900 mm and a weight of approximately 250 kg. In addition, the height of the automatic development apparatus is approximately 1250 mm; the total weight comes to roughly 500 kg. Symbol p in FIG. 23 represents a pick-up mechanism, and g represents a film conveyor means.
FIG. 24 depicts a variable density image (grey scale image) photographic apparatus i, consisting of a film feeding cassette a, a film-shape adjustment space s, and a film securing half-cylinder k, configured from top to bottom in that order, with an exposure means c located in the center of the half-cylinder k, and with an image processing, control, and power supply means m located adjacent to the film shape adjustment space s and film securing means k. An automatic development apparatus is mounted on top of variable density image (grey scale image) photographic apparatus i, so that the total height of variable density image (grey scale image) photographic apparatus i, including that of the automatic developer, comes to approximately 1,500 mm, and their combined weight comes to approximately 370 kg. Symbol p in FIG. 24 represents a pick-up mechanism, and g represents a film conveyor means.
FIG. 25 depicts a variable density image (grey scale image) photographic apparatus i, consisting of an exposure means c, a film securing drum f, a film retrieval cassette b, a film feeding cassette a, and an image processing, control, and power supply means m, configured from top to bottom in that order. For this reason, the height of variable density image (grey scale image) photographic apparatus i is approximately 1,030 mm, and its weight is approximately 180 kg. Symbol p in FIG. 25 represents a pick-up mechanism, and g represents a film conveyor means.
FIG. 26 represents a variable density image (grey scale image) photographic apparatus i, consisting of a film feeding cassette a, a film securing quarter-cylinder n with a revolving type exposure means c, and an image processing and power supply means o, configured from top to bottom in that order, with a control means q installed adjacent to the film securing quarter-cylinder n. As a result, this variable density image (grey scale image) photographic apparatus i measures roughly 1,280 mm in height, and its weight is approximately 170 kg. Symbol p in FIG. 26 represents a pick-up mechanism, and g represents a film conveyor means.
Thus, the conventional variable density image (grey scale image) photographic apparatuses i exceed 1 meter in height and weigh around 200 kg. Their large size gives rise to certain problems: they require a large space in which to be installed; efficient utilization of floor space and room space is reduced in the facilities in which they are installed; and shipping and moving of these apparatuses is a complex and expensive undertaking.
For these reasons, the advent of an easy-to-handle variable density image (grey scale image) photographic apparatus measuring less than 1 meter in height and weighing under 100 kg will be warmly welcomed by medical professionals who deal with medical equipment of this type.
In developing this invention, we have sought to learn from such problems with the prior art. The object of this invention is to offer a variable density image (grey scale image) processing method, and a variable density image processing apparatus utilizing it, which can render identifiable a single-sheet photosensitive medium on which multiple images have been made, by simply and rapidly inscribing identifying information in a designated location on the medium.
An additional object is to provide a variable density image (grey scale image) photographic apparatus which can make photographs out of images from variable density image processing apparatus and which is smaller and more lightweight, thus enhancing the efficient utilization of floor and room space in facilities in which it is installed, and improving ease of shipping and moving.